Unit 8 - IV. Karyotypes and Chromosomal Mutations - H Bio

Karyotype

• an image taken of chromosomes during mitosis

• used to identify both biological gender and possible chromosomal mutations

Human chromosomes are

numbered 1-22 and then there are sex chromosomes

Chromosomes are identified and paired according to

• centromere position

• banding pattern due to staining

• overall size (incl. arm length)

Chromosomal mutations

• occur during DNA replication and meiosis

• includes partial chromosomal mutations and whole chromosome mutations

Whole chromosomal mutations

• trisomy

• monosomy

*caused by “non-disjunction” (separation fails to occur)

Trisomy

karyotype shows an entire extra chromosome

• chromosome had an extra gamete when created, e.g. XXY

Monosomy

karyotype shows a missing chromosome

Partial chromosome mutations

• deletion

• duplication

• translocation

• inversion

Deletion

• a section of a chromosome is missing

• chromosome appears small

Duplication

• a section of a chromosome is repeated

• chromosome appears oversized

Translocation

a section of a chromosome detached and reattached to a different chromosome

Inversion

a section of a chromosome detached and reattached in the wrong direction